Currently, a system (so-called an electric license plate system) is under development to transmit and receive various data between a radio communication module fixed on a vehicular license plate and outer apparatuses (road-side units) installed on sides of roads for a registration management of vehicles, a traffic control and the like.
The radio communication module for the system is provided with a memory (storage media) to store vehicular information such as a vehicle registration number, a marque and a type of the vehicle, which are indicated in a registration card of the vehicle to which the radio communication module is installed. The radio communication module is fixed on a license plate of the vehicle so as not to be easily detached to prevent the vehicular information stored in the memory from being unauthorizedly read or tampered by a third person, or to prevent the radio communication module from being stolen, unauthorizedly reused and replaced to another vehicle (refer to JP-2001-119175-A, for example).
However, the installation constriction of the radio communication module according to JP-2001-119175-A has a relatively poor workability in fixing the radio communication module on the license plate. The installation construction requires works such as welding to fix the radio communication module on the license plate. Further, when it is necessary to detach the radio communication module from the license plate for a data maintenance, repair of failure and so on, the radio communication module cannot be easily detached from the license plate, so that the installation construction includes an issue in a viewpoint of operation and popularization of the products.